Multiplayer Peer-to-Peer Connection Across Firewalls and Network Address Translators Using a Single Local Port on the Local Host

Abstract

A system for providing peer-to-peer connections includes a plurality of host devices behind corresponding NATs; and a plurality of STUN servers. Each host device includes first and second sockets respectively bound to first and second private ports. Each host device sends a first STUN packet through the first socket to a first STUN server and a second group of STUN packets through the second socket to the STUN servers via public ports of the corresponding NAT. The STUN servers identify the public port numbers of the public ports. Each host device calculates a predicted public port number of the corresponding NAT for the second socket, based on the public port numbers of the public ports for the first socket and the second socket, the predicted public port number to be used for peer-to-peer connection between the second socket of the host device and other host devices.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application is a continuation application of, and claims priority to, U.S. patent application Ser. No. 10 / 957,122, filed Sep. 30, 2004, titled “MULTIPLAYER PEER-TO-PEER CONNECTION ACROSS FIREWALLS AND NETWORK ADDRESS TRANSLATORS USING A SINGLE LOCAL PORT ON THE LOCAL HOST”, which is incorporated by reference herein in its entirety for all purposes.BACKGROUND OF THE INVENTION[0002]The present application relates generally to communications between computer devices and, more particularly, to multiplayer peer-to-peer connections across firewalls and network address translators (NATs), using a single port number on each computer device.[0003]More and more applications attempt to create a peer-to-peer connection between two hosts to transfer data. However, it is non-trivial to achieve such a connection in case one or both of the hosts are behind a firewall, especially if it also does network address translation, as is the case with the g...

AI Technical Summary

Problems solved by technology

However, it is non-trivial to achieve such a connection in case one or both of the hosts are behind a firewall, especially if it also does network address translation, as is the case with the great majority of business and home firewalls nowadays.

The problem is even further complicated in the case where a host attempts multiple peer-to-peer connections at the same time through a single port.

An additional challenge is to be able to set up a new connection through a single (private) port of the host, all the while transferring data through that same port with other hosts.

The result is that if a host happens to be behind a difficult to traverse firewall / NAT, the host's online experience will be poor because a lot of connections will fail.

However, this is a complicated operation for the average user and potentially creates a security hole in the firewall.

Furthermore, this solution fails when two users are behind the same firewall.

Indeed, some firewalls are more difficult to traverse than others, and in the case of Microsoft® the technology will enable peer-to-peer connectivity between hosts behind “easy” firewalls / NATs, but not behind more difficult ones.

But often users already have a firewall before they buy a game.

In case they use a firewall that is not supported by the game, they will run into problems to play online.

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